A liquid reservoir 30 can be provided in a zone downstream from the condenser 8 in the refrigerant introducing path as shown in FIG. 6, such that the surface level of the liquid refrigerant in the tank 2 is lower than that of the refrigerant in the liquid reservoir. By providing the liquid reservoir 30, the pressure corresponding to the difference between the surface levels is applied to the tank 2, which helps the flow of refrigerant from the condenser into the tank 2.
By disposing a plurality of the heat pumps 1 in parallel as shown in FIG. 5, and operating them such that cooling by the cooling apparatus C and heating by the heating apparatus H of the heat pumps are performed in a timed sequence (with time difference respectively in each heat pump), total flow of vapor refrigerant discharged from the heat pumps can be smoothed.
Accordingly, there remains a need for a way of pressurizing and transferring a refrigerant, such as in a Rankine cycle system, with a lower power consumption in comparison with mechanical pump, while increasing reliability thereof by using non-moving components, resulting in absence of mechanical loss. The present invention addresses this need.